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Strange Streak in Australia

Discussion in 'Electronic Design' started by Mike Monett, Dec 7, 2004.

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  1. Mike Monett

    Mike Monett Guest

    Here's a puzzle. If anyone can solve it, you guys can.

    Astronomy Picture of the Day (APOD) has an unusual picture taken just
    after a gray streak apparently hit a streetlamp, causing a flash and
    some smoke. Investigation showed damage to the housing and the lamp had
    failed. Photos taken before and after the flash do not show the gray
    streak. The more you study it, the stranger it becomes. Here's the url:

    http://antwrp.gsfc.nasa.gov/apod/ap041207.html

    Best Wishes,

    Mike Monett
     
  2. Don Pearce

    Don Pearce Guest

    Not very convincing. The streak is constant density all the way across
    - looks digitally added to me.

    d

    Pearce Consulting
    http://www.pearce.uk.com
     
  3. Don Pearce

    Don Pearce Guest

    In fact, if you have Adobe Photoshop, use the paintbrush in black with
    appropriate thickness, then set the opacity to 1%, and you can
    reproduce the effect exactly.

    d

    Pearce Consulting
    http://www.pearce.uk.com
     
  4. NASA prankster? Not likely, imho. There are literally tons of possible
    _natural_ explanations for this one. The small flash looks alot like
    something produced in the lens, but the streak I have no good
    explanation for. An insect flying by the camera would likely explain
    this though, someone on slashdot said the EXIF says flash was fired
    (why? No idea), so the flash combined with a insect zooming by would
    explain it, however the streak is much too straight to really look like
    the path of a flying insect. The flash could probably kill small insects
    that are too close to it, Ive scarred plastic stuff by holding them
    infront of the flash, on the other hand the flas seems to be fired in
    the lowest position.

    There are lots of other possible causes: blowing bulb, shadow from a
    jetstreak (both?) or a actually, why not a meteor? :)
     
  5. Ian Stirling

    Ian Stirling Guest

    (some snipped, exif data)


    Tag |Value

    Manufacturer |Canon
    Model |Canon PowerShot G3
    Exposure Time |1/19 sec.
    Aperture |f/5.6
    Exposure Bias |0.0
    MaxApertureValue |73/32
    Metering Mode |Pattern
    Flash |Flash fired, auto mode, red-eye reduction mode.
    Focal Length |9.1 mm

    Ok, so the shutter is open quite a long time.
    1/19th second.

    Apature I make as about 2mm.

    At the shutter speed of 1/19th of a second, the flash is
    quite adequate to freeze motion.

    I'm assuming that the camera fires the flash first.

    Just to the right of the streetlight, and extending up and down, I
    see a ligher area that seems to have two "arms" pointinf up-right and
    down-left.
    This seems to continue over the light, being washed out by it,
    coming to an end just after the light.

    It's interesting that approximately normal to the 'arms', and in
    line with the extended blob centered over the light is the rest
    of the streaks path.

    Let's assume it's an insect.
    It was happily flying past (climbing, or descending if the flash
    fires last) when the flash went off as it started to bring
    its wings down, and the flashes light ended with the wings in
    the down position.

    I make the angular size of the main bright spot (call it the body)
    18 pixels across or so.
    This is about 1/100th of the picture size, which I make at about
    ..1r.
    So, call it a milliradian.
    So, the 'true' size might be half a milliradian, or if the insect
    is 1mm across (apature 2mm) maybe a meter away.

    Say the streak crosses a third of the picture, so that's .03r/.19s,
    or .15r/s, or (if a meter away) 15cm/s.

    Not an extreme speed for an insect.

    Apature is 2mm, so assuming that it's well inside focal distance,
    and the size is 2mm (the blur is not very sharp edged),
     
  6. Looks like a knat flew in front of the lens.
     
  7. Mike Monett

    Mike Monett Guest

    Very good!. Sounds quite convincing. You might post your analysis in the
    APOD forum at

    http://bb.nightskylive.net/asterisk/viewtopic.php?t=249

    Best Wishes,

    Mike Monett
     
  8. Don Pearce

    Don Pearce Guest

  9. Pooh Bear

    Pooh Bear Guest

    You mean a gnat ?

    Graham
     
  10. I read in sci.electronics.design that Pooh Bear <rabbitsfriendsandrelati
    A gnat is a million times larger than a knat.
     
  11. Lyric revision?
    'I'm a gnu, how do you do.
    'I'm a knat, how about that?'
     
  12. Pat Ford

    Pat Ford Guest

    bush might have thought that was a weapon of mass illumination and had it
    ecm'ed 8*)
    Pat
     
  13. Anders F

    Anders F Guest

    Whoops, guess my new plama ray gun do actually bounce off the atmosphere...
    But I swear: I /was/ shooting at the little blue men in their space ship ;-)

    /Anders (I'm with Don on his theory (all the way) ;-)
     
  14. I read in sci.electronics.design that Terry Pinnell <[email protected]
    What about the dzo?
     
  15. Ban

    Ban Guest

  16. I dont think this was taken hand-held, it was afaict an automated
    sequence. I guess somebody could have been there though...
     
  17. Chris Carlen

    Chris Carlen Guest


    Just because it can be created digitally doesn't mean it was.

    How do you explain the flash and cloud of smoke?


    Actually, digital photography kinda sucks because now there is always
    this doubt as to authenticity. I share your skepticism. But we still
    should be careful about the logic employed.


    Good day!



    --
    _______________________________________________________________________
    Christopher R. Carlen
    Principal Laser/Optical Technologist
    Sandia National Laboratories CA USA
    -- NOTE: Remove "BOGUS" from email address to reply.
     
  18. Don Pearce

    Don Pearce Guest

    Well, I did it in about three seconds, and it is the most reasonable
    answer.
    Probably a power line blew up, and he got a photo. He then decided to
    juice it up a bit to make it more interesting.
    The logic should always - in the absence of anything better - be that
    of Occam's razor.
    d

    Pearce Consulting
    http://www.pearce.uk.com
     
  19. Mike Monett

    Mike Monett Guest

    Don Pearce wrote:

    [...]
    Yes, of course it can be faked. But if you read the APOD description,

    "The photographer insists that the streak and flash on the above image
    has not been created digitally."

    http://antwrp.gsfc.nasa.gov/apod/ap041207.html

    So you have to believe it was not faked.

    An insect flying near the lens seems a good explanation. Now, I invite
    you to tell us what kind of insect it was, and how long it survived after
    the shutter was closed before it was eaten:)

    Best Wishes,

    Mike Monett
     
  20. Don Pearce

    Don Pearce Guest

    No I don't. I believe the obvious and simple explanation - in fact the
    one I can duplicate exactly.
    Rubbish! Have another look at the streak. It is dead straight, which
    an insect flight would not be. It is also of uniform density across
    its width - an out-of-focus image would have a tapered density from
    centre to edge. You are far too credulous and uncritical.
    d

    Pearce Consulting
    http://www.pearce.uk.com
     
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